Loosen the clamp, take off the bars, unscrew the locknut, unscrew the headset deal, take out the ball bearings and bearing cage, pull the fork out the bottom of the headtube, take the ball bearings off of the fork.
If you're planning on putting the whole headset on another deck and fork, then bang off the crown race (thing on the fork at the bottom of the downtube that will probably have grease on it), and take a flathead screwdriver and a hammer to bang out the bearing cups (round things sticking out of the head tube). Store all of it in a plastic bag or something so that it doesn't get all dirty.